New patented fuel treatment and feeding system

 

New patented fuel treatment and feeding system for Diesel oil aggregates with Common-Rail-injection unit

Definition of problem

Engines with Common-Rail injection technology require a high fuel quality for their high-pressure pumps and injection nozzles. Particles and water content in the fuel are reducing the operating time of the motor main-filter down to 60 – 80 hrs.

Safety filter for withhold of 30µm, which are pre-switched at the system of a well known Motor maker, showed mostly unpolluted because dirt-particles are < 30 µm. Free water will be admittedly discharged up to > 500 ppm, but (the absolute normal) fuel/water emulsions are not separated.

But if the water content in the fuel is exceeding 80ppm, the water is collecting in the engine main filter. The filter paper is swelling, showing s-form and is blocking or better water is transported to the high-pressure pump and injectors.

Increased water-content leads to corrosion in the high-pressure pump and injectors, which is reducing the lifetime significantly. The solid particles, which are remaining due to minor filtering-grades, plus water content of fuel before the pressure pump and injectors in connection with the very high injection pressure are causing mechanical wear at these components.
 

Requirements of motor maker

As the presently used "filter water separator" are working in suction-modus and no substantial amendments in construction should be made, the motor maker demanded to "jump over this constructive hurdle" by using the NFV-technology. During a 2 years period of planning and construction NFV developed a method which conforms will all requirements.

The solution

Overview KFWA unit (click on image for bigger view )

Function principle

The KFWA can be operated in 3 different ways.

a  Normal operation
b  Operation with soiled filter- coalescer-element
c  Operation during power failure (Emergency)

(click on image for bigger view )


This KFWA is a filter- coalescer- type.
The gear wheel pump will transfer the fuel through the filter- coalescer- element from the inside to the outside. This coalescer cleans the fuel in two ways. First by filtering and second by de-watering. The de-watering stage consists of a hydrophil material which is able to collect very small drops of water on its surface and structure. After a while the small drops conglomerates to bigger drops of appr. 3 mm so they are able to sink down to the bottom of the KFWA -housing.

The separated water will be detected by a water level sensor which operates water drain valve. To evacuate the separated water the pressure retaining check valve at the outlet of the unit keeps the pressure stable in the housings at 0.5 bar.

The water drain valves opens and closes while the unit is under operation. There is no need to stop the engine. It is not necessary to deaerate the unit after draining because it´s fully automatic.

The impurification of the combined filter and coalescer cartridge will be monitored via a differential pressure switch. If the differential pressure reaches 1,5bar an alarm will register, indicating that it is necessary to change the element. To calculate the differential pressure manually there are two manometers mounted, one in the inlet and one in the outlet.

In most cases the motor fuel pumps are sensitive regarding pressure fluctuation at the suction side. To separate the KFWA from the engine due to pressure and power fluctuation the fuel flows through a pressure-free overflow tank from which the engine fuel pump will draw fuel.

Conclusion

The NFV Fuel Treatment KFWA is a unit for purifying middle-distillates of injection systems from diesel engines and gas turbines by filtration and water separation. It consists of a combination between one or two feeding pumps with minimum one filter-water-separation-unit which is equipped with one installed filter-water-separator-element ,one water-discharge-device and one differential pressure switch. Furthermore a overflow-suppression-tank with an automatic overflow is planned. All sequences ensue automatically.

Test phase

The first NFV units have been tested by the motor maker on "problem ships", all test and examinations had been accompanied by neutral laboratories and Institutions.

Experimental assembly NFV-Filter KFWA 1800

Version 2 in side-flow ( i.e. with daily tank)

The NFV filter is arranged between bunker tank and daily tank. The fuel samples were taken directly before and behind the filter as well as at the fuel filters cultivated in series at the engines.



Arrangement of the NFV filter with sample points


Simplified fuel pattern for ships with daily tank (side flow)
(click on image for bigger view )

 

Conclusion

 

In the meantime 23 plants for the engine manufacturer were supplied and tested successfully in practice. In the meantime the release of the motor maker is present, like also those of the Certification Society, like GL and others.


Kfm.-Ing. Eberhard Runge

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